Roughly chop the spinach, then squeeze it out well in a tea towel. Put in a bowl and mix well with 100 g parmesan, egg yolk, mascarpone, semolina and flour. Season with salt, pepper and nutmeg. Let the mixture steep for 20 minutes.
Shape the mixture into small dumplings and roll them in flour. Simmer in salted water for approx. 8 minutes.
Arrange on plates with the remaining freshly grated Parmesan and brown butter and serve immediately.